1. Field
The present disclosure relates generally to manufacturing and in particular to fastening parts to each other. Still more particularly, the present disclosure relates to a method and apparatus for a fastening system with a positive retention mechanism.
2. Background
A fastening system has one or more hardware devices used to mechanically join and/or attach two or more parts together. For example, a fastening system may include a rivet, a screw, or a bolt and nut combination. A bolt typically has external threads designed to be inserted through a hole in assembled parts. The bolt may be tightened or released using a nut that engages the threads.
Bolts are used in aircraft manufacturing to secure various parts in the aircraft to each other. For example, a bolt and nut may be used to secure a stringer to a rib. As another example, a bolt and nut may be used to secure an electrical module to a structural component in the aircraft.
In some applications, a locking nut is used to help ensure that the bolt and nut do not become disengaged from each other. A locking nut may be used in which a portion of the nut has a slightly oval shape relative to a circular shape of the bolt. In other implementations, the nut on the end of the bolt on one side of the structure and the opposite end of the bolt on the other side of the structure may both be secured to prevent either of the components from turning. These structures are objects other than the parts being secured by the bolt and the nut.
The securing of the bolt and the nut to other structures are used to prevent rotation of both the bolt and nut. In yet other examples, the structures may allow some rotation but prevent separation of the components. In still other applications, two or three bolts and nuts may be used instead of a single bolt and nut system to provide additional redundancy.
In yet other applications, adhesives may be placed into the threads to lock the bolt and nut in place as yet an additional mechanism to prevent rotation of the bolt and nut. These adhesives may include, for example, an adhesive resin that may harden in the absence of air. An example of this type of resin is a Loctite® resin. Loctite® is a registered trademark of the Henkel Corporation. Patch elements and cotter pins also may be used to provide additional features to limit movement of a bolt and/or nut.
Although these types of systems provide additional redundancy to insure that parts are secured to each other, these types of systems may be complex and may add weight to the aircraft. For example, if a particular structure in an aircraft normally uses 1,000 bolts and nuts, to add an additional bolt and nut to each of those would greatly increase the weight of the aircraft.
In another example, it may be difficult to locate space or structures to which both the bolt and nut can be secured to prevent the bolt and nut from turning.
The use of cotter pins requires a hole to be present through the nut and bolt. Fastener strength requirements may prevent the use of this type of fastening mechanism. Further, environmental exposure may make it unfeasible to use a resin-based retention mechanism.
Therefore, it would be advantageous to have a method and apparatus to overcome the problems described above.